Describe clinical findings in sufficient detail for a meaningful evaluation to be made.

Separate levels of evidence scores are assigned to qualifying human studies on the basis of statistical strength of the study design and scientific strength of the treatment outcomes (i.e., endpoints) measured. The resulting two scores are then combined to produce an overall score. An overall level of evidence score cannot be assigned to cannabinoids because there has been insufficient clinical research to date. For an explanation of possible scores and additional information about levels of evidence analysis of CAM treatments for people with cancer, refer to Levels of Evidence for Human Studies of Cancer Complementary and Alternative Medicine.

There have been only three small clinical trials on the use of Cannabis in cancer patients. All three studies assessed antiemetic activity but each explored a different patient population and chemotherapy regimen. One study demonstrated no effect, the second study showed a positive effect versus placebo, and the report of the third study did not provide enough information to characterize the overall outcome as positive or neutral. Consequently, there are insufficient data to provide an overall level of evidence assessment for the use of Cannabis for chemotherapy-induced N/V. Apparently, there are no published data on the use of Cannabis for other cancer-related or cancer treatment–related symptoms.

An increasing number of trials are evaluating the oromucosal administration of whole Cannabis plant extract with fixed concentrations of cannabinoid components.

At present, there is insufficient evidence to recommend inhalingCannabis as a treatment for cancer-related symptoms or cancer treatment–related side effects.